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Re: AW brand 10440's now with Soshine label ?

Originally Posted by The Dane

No!
Around 3V is 5% from dead. And 4.08V is 5-7% from full.
3.7V is the average voltage of the LiPo cell type.

Might want to rethink that 3V figure. There's lots of testing information on rcgroups.com which points to 3.6V being depleted. I will say, however, they're generally pushing LiPo with a high C discharge, but still, Voltage is a very good indicator of charge level. There are manufacturers who do state the cutoff is 3.0V, but that's for CAPACITY testing, not normal everyday use.

Re: AW brand 10440's now with Soshine label ?

Originally Posted by clintb

Might want to rethink that 3V figure. There's lots of testing information on rcgroups.com which points to 3.6V being depleted. I will say, however, they're generally pushing LiPo with a high C discharge, but still, Voltage is a very good indicator of charge level. There are manufacturers who do state the cutoff is 3.0V, but that's for CAPACITY testing, not normal everyday use.

I believe the 3.0V cutoff is usually quite good for normal use. Many manufacturers have it set much lower and too low for my moderate-current needs (e.g. AW at 2.5V). The cutoff voltage is under load, it's lower than the battery voltage would be when the load is removed.

I'm not sure if the voltage is a good indicator of the charge level for almost depleted cells. I think it is universally agreed that ~2.8V or lower cell resting voltage (i.e. without the load and after a rest period when the voltage can recover) indicates an overdischarged cell. I think ~3.2V usually means that the cell is empty but not overdischarged. 3.6V may indicate that a bit of energy is left but really not much - for practical purposes it can be considered empty.

4.08V-4.12V probably means that the cell after 24h holds up ~80%-90% charge. I don't know what it means and how the cells behave but after 4 years, no one should complain even if they were already completely dead

Re: AW brand 10440's now with Soshine label ?

4.08 is kinda low . Not much in reserve ? Isn't 3.70 considered DEAD ??

I have always kept my Li-Ion's in the fridge at 35-40F (regardless of chemistry) when not in use. This appears to make a big difference in longevity, in my experience.

As for the condition of a LiCO Li-Ion cell. After charging to 4.20 Volts and then letting the cell rest for a few hours (I let them sit for 24hrs) the condition of the cell can be determined by the voltage.

4.20 Volts is new or 100%

4.10 Volts 90%

4.00 Volts 80% Below this voltage the cell should be recycled.

Dave

EDIT:

The above proceedure is for determining the condition of a LiCO Li-Ion cell.

To determine the remainingcapacity of a LiCO Li-Ion cell, measure the OC voltage of the rested cell.

Re: AW brand 10440's now with Soshine label ?

Originally Posted by 45/70

As for the condition of a LiCO Li-Ion cell. After charging to 4.20 Volts and then letting the cell rest for a few hours (I let them sit for 24hrs) the condition of the cell can be determined by the voltage.

4.20 Volts is new or 100%

4.10 Volts 90%

4.00 Volts 80% Below this voltage the cell should be recycled.

I think that none of my cells was able to hold exactly 4.20V. Even when new they were dropping to something around 4.18V-4.19V.

I haven't tested it but I think that the problem with this method may be in the fact that the cell has to be fully charged for it to work. If the charger doesn't use the correct CC/CV algorithm but some strange invention (like most cheaper chargers do) it's quite possible that it doesn't fully charge the cell. Even if the battery is working perfectly, it may not hold the expected voltage simply because it wasn't correctly charged.

Re: AW brand 10440's now with Soshine label ?

Originally Posted by clintb

Might want to rethink that 3V figure. There's lots of testing information on rcgroups.com which points to 3.6V being depleted. I will say, however, they're generally pushing LiPo with a high C discharge, but still, Voltage is a very good indicator of charge level. There are manufacturers who do state the cutoff is 3.0V, but that's for CAPACITY testing, not normal everyday use.

with the high discharge RC batteries with the fat plates and all, the numbers are different. I usually use the big 2c max batteries , but they didnt have some in the size i wanted, and i got high discharge ones instead like the 10C type, and the discharge curve (especially under load) is hugely different. and MY load is not different, and my load is well below 1c even. Basically RC batteries are hugely different then most of the stuff were using. High C batteries are not the highest capacity for weight/size ratio, they are built for speed discharge (and charge)

so not only the rate they use them, but the way the cell is built can make a difference.
it certannly makes a difference in the numbers.

i swear this is related to the little tiny cells all crammed into little tiny packages, so this really isnt as off topic as it sounds :-)

Re: AW brand 10440's now with Soshine label ?

Originally Posted by wapkil

I think that none of my cells was able to hold exactly 4.20V. Even when new they were dropping to something around 4.18V-4.19V.

I haven't tested it but I think that the problem with this method may be in the fact that the cell has to be fully charged for it to work. If the charger doesn't use the correct CC/CV algorithm but some strange invention (like most cheaper chargers do) it's quite possible that it doesn't fully charge the cell. Even if the battery is working perfectly, it may not hold the expected voltage simply because it wasn't correctly charged.

Yeah, I've had cells from AW that actually could hold 4.20 Volts after a day, but most will drop to 4.18-4.19 Volts, even when new. I believe this is just that cell degradation has started. And yes, you do need a charger that properly charges cells to 4.20 Volts.

I should point out that when checking remaining capacity, the figures from 3.80 Volts and lower have been shown to have increasing inaccuracy due to differences between manufacturers cells.

Re: AW brand 10440's now with Soshine label ?

Originally Posted by 45/70

Yeah, I've had cells from AW that actually could hold 4.20 Volts after a day, but most will drop to 4.18-4.19 Volts, even when new. I believe this is just that cell degradation has started. And yes, you do need a charger that properly charges cells to 4.20 Volts.

I should point out that when checking remaining capacity, the figures from 3.80 Volts and lower have been shown to have increasing inaccuracy due to differences between manufacturers cells.

Re: AW brand 10440's now with Soshine label ?

Originally Posted by VidPro

with the high discharge RC batteries with the fat plates and all, the numbers are different. I usually use the big 2c max batteries , but they didnt have some in the size i wanted, and i got high discharge ones instead like the 10C type, and the discharge curve (especially under load) is hugely different. and MY load is not different, and my load is well below 1c even. Basically RC batteries are hugely different then most of the stuff were using. High C batteries are not the highest capacity for weight/size ratio, they are built for speed discharge (and charge)

so not only the rate they use them, but the way the cell is built can make a difference.
it certannly makes a difference in the numbers.

i swear this is related to the little tiny cells all crammed into little tiny packages, so this really isnt as off topic as it sounds :-)

I will agree there's still life in the cell after 3.60V, but it's declining rapidly after that. On my iCharger 208B that's feeding LogView, the voltage curve falls off quick after 3.6V, even at just a 1C discharge, and that's with AW 2200mAh 18650's. Will there be damage to the cell under 3.6V? In the case of a single cell, not likely if the discharge to 3.0V is hit then discontinued. Am I going to worry about it? Not really; I already have too many Li-Ion cells. Besides, they're cheap.

Re: AW brand 10440's now with Soshine label ?

Originally Posted by mr.snakeman

And who has such a charger? I want one now!

A charger that stops precisely at 4.20V? Hobby charger; namely, the iCharger line. Latest firmware lets you calibrate voltage at the charging leads, input power leads, and the balancing taps. How's that for precision? Oh, and you can dial in whatever cut-off voltage you want.